If railway switches are to function during winter conditions it is required that they are kept free from snow and ice.
The switches have earlier been kept clear by manual shoveling and sweeping. However, with rising work costs this became an unsatisfactory solution.
Later on electrical heating of sensitive parts of the switch were utilized to melt snow and ice so that the switch could function. This solution has also been found to be burdened with serious weaknesses. The energy consumption makes this solution expensive, and furthermore the melted ice often gives rise to ice water formations which disturb the function of the switch. Finally, due to reasons of economy, the electrical heating can not be dimensioned for particularly cold and snowy periods which nearly always occur at some time or times during each winter. During these periods the electrical heating is insufficient to ensure the function of the switch.